Nasa's Curiosity Rover has been on Mars for five years

In August 2012, the Nasa rover Curiosity touched down on the surface of Mars. The size of a Mini Cooper, it's four times as heavy as predecessors Spirit and Opportunity, and comes with a large robot arm, a laser that can vaporise rocks at seven metres, a percussive drill and a weather station. Oh, and 4.8kg of plutonium-238.

"We're stepping it up this time," John Grotzinger, project scientist on the Mars Science Laboratory mission, said in 2011. In 2004, the field geologist discovered water on Mars as part of the Spirit and Opportunity missions. "It's fairly common to find evidence for water on Mars now," he says.

"So we're going to the next level – the search for organic compounds as a telltale sign that there may have once been life on Mars." It's a task Grotzinger compares to "looking for a needle that has dissolved in a haystack".

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Curiosity is able to gather samples drilled from rocks or scooped from the ground and distribute them to onboard test chambers during the 687 Earth days it spends on Mars.

Since it landed on the Red Planet, Curiosity has trundled miles across the rocky terrain, captured thousands of images, and conducted numerous scientific experiments. "The mission accomplished its main goal in less than a year," Nasa says on its website. "It determined that an ancient lake environment on this part of Mars offered the conditions needed for life – fresh water, other key chemical ingredients and an energy source".

Following the early success, the Rover has been continuing to explore the surface of Mars, analysing the rocks and terrain around it. Going forward, Curiosity will be exploring the Vera Rubin Ridge and its clay and sulfate layers.

This article was originally published in the July 2011 edition of WIRED and has been updated since.

Curiosity 1

The three-metre, 890kg rover is powered by a radioisotope generator.The decay of 4.8kg of plutonium dioxide will provide a steady source of heat, used to produce onboard electricity. This means the rover can continue its mission at night, unlike earlier solar-powered craft, whose panels could be obscured by Martian dust.

Curiosity 2

Spacecraft built in the Jet Propulsion Lab at Pasadena have observed the Moon, Venus, Mars, I Jupiter, Saturn and the outer solar system. Here, technicians work on the Mars Science Laboratory’s flight system in a clean room. Two thousand technicians and scientists have worked on the project over the past six years.

Curiosity 3

Neil Laugen is a flight 3 technician at the Jet Propulsion Lab. At 21 years old, he’s the youngest member of the team that assembles the rover. “I’ve worked on other satellite projects, but nothing compares to MSL. It’s like building a giant robotic RC car,” he says. “Only it weighs a tonne and costs $2.5 billion [£1.5 billion].”

Curiosity 4

Earlier rovers bounced on to the surface of Mars using air bags. Curiosity is too heavy for that, so will use a jet backpack for the final part of its descent. As the retro rockets control the landing speed, the descent stage will unspool tethers to lower the rover’s wheels on to the surface. “If it works, it will be spectacular,” says Grotzinger.

Curiosity 5

Errin Dalshaug, left, and 5 Brett Kennedy, of JPL, prepare to assess vibration in a test model of the robotic arm. It will wield a drill, a magnifying lens camera, an element-identifying spectrometer and a rock brush. “This arm is strong,” says Kennedy, “but still needs to move accurately enough to drop an aspirin into a thimble.”

Curiosity 6

The backshell forms the top portion of the capsule that will enclose the rover and descent stage to protect them from the heat of falling through the upper atmosphere of Mars at supersonic speed. The bottom portion – the heatshield proper – will be joined to the backshell at Kennedy Space Center, Florida, ahead of launch.